Seabound is a climate tech startup that makes carbon dioxide (CO₂) capture equipment for ships to help the shipping industry meet new global regulations that require a 40% reduction in CO₂ emissions by 2030. The company’s equipment fits onto existing ships and captures up to 95% of the CO₂ emissions by using low-cost, non-toxic solid sorbents. The captured CO₂ sorbents can be disposed of safely or used for other purposes.
Challenges: carbon capture in the shipping industry
Shipping industry carbon emissions
The shipping industry is a significant contributor to global greenhouse gas emissions, accounting for approximately 3% of total emissions. Given that the shipping industry is responsible for transporting over 80% of global commerce, this is a substantial contribution. Container ships emit approximately 1 billion metric tons of carbon dioxide (CO₂) annually.
While measures approved by the International Maritime Organization are likely to slow the growth of emissions in the 2020s, more ambitious policies are needed to steer the maritime shipping sector onto the pathway of emission reductions and to encourage the adoption of low- and zero-carbon fuels and technologies, such as carbon capture, for oceangoing vessels.
How to reduce carbon emissions in the shipping industry?
Several important methods exist to reduce carbon emissions in the shipping industry.
Fuel efficiency improvement is one of the most effective methods. This can be achieved by utilizing more efficient engines, optimizing ship design, and adopting sluggish steaming practices.
Utilizing alternative fuels that produce fewer emissions than traditional fossil fuels is another option. Alternative fuels include liquefied natural gas (LNG), hydrogen, and biofuels, among others.
Fuel cells are an emerging technology that can produce electricity from hydrogen with zero emissions. Fuel cells can be used to power a ship’s propulsion system or auxiliary systems.
Wind propulsion systems, such as sails or rotors, can be used to reduce a ship’s reliance on fossil fuels and reduce emissions. These systems can be retrofitted onto existing ships or incorporated into new ship designs. Hybrid and electric propulsion systems can reduce emissions by using batteries or other energy storage systems to power a ship’s propulsion or auxiliary systems.
Carbon capture and storage (CCS) technology allows ships to capture CO₂ emissions from their exhaust gasses and store them safely. Captured CO₂ can be used in various applications, such as enhanced oil recovery or industrial processes.
What is carbon capture in shipping?
In the shipping industry, carbon capture technology is a developing area of investigation. The shipping industry is presently evaluating a number of important carbon capture technologies, including post-combustion carbon capture, pre-combustion carbon capture, oxy-fuel combustion, solid adsorbent capture, chemical looping combustion, and membrane separation.
- Post-combustion carbon capture
The post-combustion carbon capture involves removing CO₂ from flue gasses after the fuel has been burned in the ship’s engine. The exhaust gasses are first treated with a solvent, which absorbs the CO₂ from the gas stream. The solvent is then heated to release the CO₂, which can then be compressed and stored for transport to storage facilities or for use in other applications.
One of the advantages of post-combustion CO₂ capture systems is that they can be retrofitted onto existing ships, making them a more practical option for reducing carbon emissions in the shipping industry. However, post-combustion systems can be energy-intensive and require a substantial amount of space and apparatus onboard the ship, limiting their applicability to smaller vessels.
- Pre-combustion carbon capture
Pre-combustion carbon capture involves capturing CO₂ emissions before they are released into the atmosphere. This is achieved by reforming the ship’s fuel (usually heavy fuel oil) into hydrogen and CO₂. The CO₂ is then captured and stored, while the hydrogen is used as fuel for the ship’s engines.
Pre-combustion CO₂ capture systems are generally more energy-efficient than post-combustion systems because they can capture a higher percentage of the CO₂ produced by the combustion process. However, pre-combustion systems can require significant space and equipment onboard the ship, which may limit their feasibility for smaller vessels.
- Oxy-fuel combustion carbon capture
The oxy-fuel combustion process involves burning the ship’s fuel in a mixture of oxygen and recycled flue gas, which results in a flue gas stream that is primarily made up of CO₂ and water vapor. The water vapor is condensed out of the flue gas stream, leaving a highly concentrated stream of CO₂ that can be compressed and stored for transport to storage facilities or for use in other applications.
Oxy-fuel combustion CO₂ capture systems can be more energy-efficient than post-combustion systems because they do not require a solvent to capture the CO₂. However, oxy-fuel combustion systems can require significant space and equipment onboard the ship, which may limit their feasibility for smaller vessels.
- Solid adsorbent carbon capture
Solid adsorbent capture systems involve capturing CO₂ emissions from the ship’s engines using a solid adsorbent material. The solid adsorbent material used in these systems typically has a large surface area and a high affinity for CO₂. The ship’s exhaust gas is passed over the adsorbent material, which adsorbs the CO₂ from the gas stream. The adsorbent material can then be regenerated by heating it, which releases the CO₂ and allows the material to be reused for further CO₂ capture.
Solid adsorbent capture systems can be energy-efficient. Additionally, the adsorbent material can be easily transported and stored, making it an attractive option for use on ships. However, the adsorbent material can be expensive, and the process may not be as effective as other technologies at capturing CO₂ at low concentrations. Additionally, the adsorbent material may degrade over time and require replacement, which could add to the costs of the system.
- Chemical looping combustion carbon capture
Chemical looping combustion (CLC) capture system involves the use of a metal oxide, such as iron or nickel oxide, which acts as an oxygen carrier, to separate CO₂ from the ship’s engines exhaust gasses. The metal oxide transfers oxygen from the air to the fuel, resulting in combustion without the need for excess air. The metal oxide is then regenerated through a reaction with steam or CO₂, which releases the captured oxygen and produces a stream of concentrated CO₂ that can be captured and stored.
CLC capture systems can be energy-efficient and reduce the amount of nitrogen oxide (NOₓ) emissions, which are harmful to human health and the environment. However, this process requires high temperatures, making it difficult to integrate into existing ship engines. Additionally, the metal oxide used in the process can be expensive and may degrade over time, requiring replacement.
- Membrane separation
Membrane separation capture systems remove CO₂ from a ship’s exhaust gas by passing it through a membrane that enables CO₂ to pass through while leaving behind other gasses, such as nitrogen and oxygen. The CO₂ is then collected and stored for reuse or sequestration.
Membrane separation capture systems can be easily integrated into existing ship engines and operate at relatively low temperatures and pressures. However, the membranes used in the process are expensive and may need to be replaced over time. Additionally, the membranes may not be able to handle the high flow rates and pressures associated with shipping engines, which could limit their effectiveness.
Seabound develops a carbon capture technology that separates CO₂ from the ship’s exhaust emissions by using a low-cost solid adsorbent material of lime (CaO). Seabound’s carbon capture system is compact and can be easily integrated with the ship’s engine and funnel. The image below shows a prototype of Seabound’s shipboard capture apparatus.
The CO₂ in the engine’s exhaust chemically reacts with calcium oxide (CaO) pebbles, which then become limestone (CaCO₃). The limestone pebbles are temporarily stored onboard before the ship returns to port. Once back in port, the limestone pebbles are offloaded and either sold in pure form or turned back into lime and CO₂, with the lime being reused on another ship and the CO₂ being sold for utilization or sequestration.
Using low-cost lime pebbles for carbon capture is one of the advantages of Seabound’s technology. The lime pebbles are safe, inert, non-toxic, and abundantly available around the world. The lime pebbles can be easily transported and stored. Note that some Direct Air Capture companies, including Noya and Heirloom Carbon, use low-cost lime material in their technology to directly capture CO₂ from the air.
Additionally, Seabound’s carbon capture system does not require any energy-intensive CO₂ separation, compression, or liquefaction onboard, making it an attractive option for use on ships due to its energy efficiency and reduced space requirements.
The global carbon capture and sequestration market is projected to grow from $2.01 billion in 2021 to $7.00 billion in 2028 at a CAGR of 19.5%. The onboard carbon capture system market is also expected to grow, with ships and maritime segment accounting for the largest revenue share in 2022.
Seabound has built working land-based prototypes and is constructing large-scale onboard pilots in 2023. Seabound’s business model includes selling the carbon capture equipment to ship owners and selling the captured CO₂, sharing the profits with ship-owners to offset the initial hardware cost.
Seabound has raised a total of $4.4M in funding over 2 rounds, including
Their latest funding was raised on May 26, 2022 from a Seed round.
Seabound is funded by 10 investors, including
- Y Combinator
- Soma Capital
- Lowercarbon Capital
- Rebel Fund
- Leap Forward Ventures
- Emles Venture Partners
- Hawktail Management
- Eastern Pacific Shipping
- Eastern Pacific Accelerator
Alisha Fredriksson is CEO.
Seabound Board Member and Advisor
Roujia Wen is Board Member.